42 replies to this topic

[GroovyBee]

Just to be pedantic its not 2600 mode. Its a change in graphics colour depth resulting in the graphics data being used up twice as quick.

[toiletunes]

I also have the half-wide glitch. I haven't played much, but so far the glitch is on more than off. It's kind of a surprise when I suddenly see a nice helicopter or tank, etc for a fraction of a second- Then everything is smooshed again.

Wonder what effect (if any) XM will have...

Edited by toiletunes, Sat Jan 29, 2011 4:54 PM.

[toiletunes]

Okay, I finally got 2 copies of the game and 2 consoles-

One console plays both games no problem (so far, further testing may be required)

The other console has issues with one game, not the other.

The glitchy game has 1987 copyright, the other game has 1988 copyright.

SN for glitchy console A1 89 5484225
SN for other console 72R4BR A1 ?? (could be B something or 8 something, very faded/worn) 5261631

Hope this helps...

[AtariLeaf]

toiletunes, on Sat Jul 9, 2011 12:09 PM, said:

Okay, I finally got 2 copies of the game and 2 consoles-

One console plays both games no problem (so far, further testing may be required)

The other console has issues with one game, not the other.

The glitchy game has 1987 copyright, the other game has 1988 copyright.

SN for glitchy console A1 89 5484225
SN for other console 72R4BR A1 ?? (could be B something or 8 something, very faded/worn) 5261631

Hope this helps...

Interesting so perhaps a certain combination of 7800 motherboard revision and Choplifter cart version is causing these problems.

[Atari Joe]

I hate to say they did a shit job of porting Choplifters! to the 7800. Have you seen it on the Sega Master System? It looks great. The 7800 was always capable of so much more than what was ever programmed for it the Jaguar too.

[toiletunes]

Just opened up the consoles:

Rev A works fine
Rev C has the glitch

[toiletunes]

Last update-

I got another copyright 1987 Choplifter, and it had the same glitch with the rev c 7800.

[GroovyBee]

Is it possible to get a dump of the offending carts so that the differences can be compared?

[Mitch]

It wouldn't surprise me if it had more to do with the speed of the chip than the contents of the ROM. Though I'd still be happy to dump it if it was mailed to me.

Mitch

[toiletunes]

pm incoming

[AtariLeaf]

Glad to see that it seems to be something other than defective hardware at play here. So it seems 1987 versions of choplifter don't play nice with Rev C 7800 motherboards, albeit a small sample size of course but still. . .

[tz101]

A little off topic, but still related: I bought Pac Man Collection from the AA store a couple months back. When it arrived, I tried it out and there were garbled characters all over the title screen, along with two horizontal black stripes that went through the mazes when I played. I cleaned my system contacts along with the cartridge pins, to no avail, and yet all my other 7800 and VCS games worked fine in this console. I contacted Al and sent the game back for a replacement. The replacement arrived, and the results were the same: Garbled characters on the title screen and black stripes through the playfield during game play. Al stated that he thought it was something with the "board" inside that batch of Pac Man Collection carts, and that he would send me one from a different batch of PCB's soon. The game arrived with the new board inside about a week ago, and it works flawlessly. What is different about my 7800 console? I don't know, but wonder if different "versions" of 7800 consoles could be causing the problems seen in the OP.

[AtariLeaf]

Atari Joe, on Sat Jul 9, 2011 1:49 PM, said:

I hate to say they did a shit job of porting Choplifters! to the 7800. Have you seen it on the Sega Master System? It looks great. The 7800 was always capable of so much more than what was ever programmed for it the Jaguar too.

You're right Joe, same with Rampage. By far the best version is on the SMS IMO. Although I do like the 7800 Muppet Babies Rampage too

[toiletunes]

I sent the carts to Mitch, here's what Mitch had to say:

"I dumped them all and they all are an exact match for the existing dump. I took apart the one that had the hole over the screw and it had a resistor on the +5v line. So it's possible that there was a run of chips that had an issue and they had to use a resistor to drop the juice to the ROM chip. Maybe the incompatible consoles don't have clean enough power to make it work properly. But that's just a guess."

The cart with the screw hole was 1987.
When I got the carts back, I opened up the other two-
Both 1987 carts had the resistor, the 1988 did not.

Thank you Mitch for your help

[gdement]

That's weird, I wonder how a resistor was supposed to be helpful. I've never heard of memory devices working better when you drop the voltage, only worse.

[GroovyBee]

Any chance of an up close and in focus photo of the PCB around the resistor area? We might be able to work out what its connected to.

[toiletunes]

pm incoming

[GroovyBee]

From a chat with toiletunes it appears that the PCB is rev B (with resistor) on this page :-

http://www.atarihq.c...t/C024926.shtml

Schematic here :-

http://www.atarihq.c...art/C024926.pdf

The resistor is 150 ohms.